From 8c444bac604da522cd216d93c611eb2b7800bd9a Mon Sep 17 00:00:00 2001 From: Helmut Grohne Date: Mon, 23 Sep 2024 09:52:14 +0200 Subject: [PATCH] FAQ: Why is backing up an unmodified FAT filesystem slow on Linux? --- docs/faq.rst | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/docs/faq.rst b/docs/faq.rst index e3de4bf95d..5fc3a83a2a 100644 --- a/docs/faq.rst +++ b/docs/faq.rst @@ -357,6 +357,16 @@ to change them. Use ``borg repo-compress`` to efficiently recompress a complete repository. +Why is backing up an unmodified FAT filesystem slow on Linux? +------------------------------------------------------------- + +By default, the files cache used by BorgBackup considers the inode of files. +When an inode changes compared to the last backup, it hashes the file again. +The ``vfat`` kernel driver does not produce stable inodes by default. One way +to achieve stable inodes is mounting the filesystem using ``nfs=nostale_ro``. +Doing so implies mounting the filesystem read-only. Another option is to not +consider inodes in the files cache by passing ``--files-cache=ctime,size``. + Security ########